JEE MainChemistryp Block Elements (Group 13 & 14)
Given below are four statements regarding the physical properties of Group 13 elements: (A) Boron is a non-metal and is extremely hard. (B) The melting point decreases continuously from Boron to Thallium. (C) Gallium has an unusually low melting point but a very high boiling point. (D) The high melting point of Boron is due to the presence of strong metallic bonds. Choose the correct answer from the options given bel
Options
- A(A), (B) and (C) only
- B(A) and (D) only
- C(A) and (C) only
- D(B) and (D) only
Correct answer
C. (A) and (C) only
Step-by-step solution
Statement (A) is correct: Boron is a non-metal and is extremely hard due to its strong covalent network structure. Statement (B) is incorrect: The melting point does not decrease continuously down the group. It decreases from Boron to Gallium, and then increases from Gallium to Thallium. Statement (C) is correct: Gallium has an unusually low melting point (approx 303 K) and can exist as a liquid during summer, but it has a very high boiling point (approx 2676 K), making it useful for high-temperature thermometry. S